This invention relates to use of dimensionally unstable materials which undergo a predictable and controlled change in shape under certain conditions. By confining such a material, large residual forces are developed as the material strains to undergo a change in shape. These residual forces are utilized to grip and align waveguides which are to be colinearly spliced end to end.
One suitable material comprises any of the noncrosslinked or crosslinked polymers, or copolymers such as, polyethylene, polyvinyl, chloride, and polyolefins, which are described in representative U.S. Pat. Nos. 3,359,193; 3,370,112, and 3,616,363. Also useable are amorphous polymers, such as polystyrene, crystalling materials with a low degree of crystallinity, such as polyvinyl chloride, slightly crosslinked crystalline polymers and copolymers having high degrees of crystallinity, such as Nylon, polyethylene, Kynar, Valox. These are heated and then resiliently stretched, sometimes biaxially, then cooled. The polymers are dimensionally unstable in their stretched form. Upon the application of heat they recover their original unstretched shaped.